Acoustic web

Abstract

Pore plugging is reduced when laminating an airflow resistive membrane to a thermoplastic hot melt adhesive, by treating the membrane to reduce its surface energy. This enables fabrication of acoustical laminates incorporating substantial amounts of recycled fibrous insulating mat manufacturing waste, and permits design of the laminate based primarily on one-quarter wavelength sound absorption considerations and control of the porosity and interfacial adhesion of the airflow resistant membrane.

1 . A porous laminate comprising a discontinuous hot melt adhesive layer adhered to a semipermeable low surface energy airflow resistive porous membrane whose pores are substantially impenetrable by the adhesive.  
   
   
       2 . A porous laminate according to  claim 1  wherein the porous membrane has a surface energy less than about 34 dynes/cm 2  and an acoustical airflow resistance between about 200 mks Rayls and about 3300 mks Rayls.  
   
   
       3 . A porous laminate according to  claim 1  wherein the porous membrane has a surface energy less than about 34 dynes/cm 2  and an acoustical airflow resistance between about 600 mks Rayls and about 1100 mks Rayls.  
   
   
       4 . A sound-absorbing laminate having a porous sound-absorbing spacing layer adjacent to a semipermeable airflow resistive membrane that is substantially impenetrable by molten polyethylene.  
   
   
       5 . A sound-absorbing laminate according to  claim 4  wherein the airflow resistive membrane has an acoustical airflow resistance between about 200 mks Rayls and about 3300 mks Rayls.  
   
   
       6 . A porous laminate comprising a thermoplastic adhesive layer adjacent to a semipermeable fluorochemically-treated airflow resistive membrane.  
   
   
       7 . A porous laminate according to  claim 6  wherein the adhesive comprises a polyolefin and the airflow resistive membrane comprises a meltblown polyamide or polyester nonwoven web having an acoustical airflow resistance between about 200 mks Rayls and about 3300 mks Rayls.  
   
   
       8 . A porous laminate according to  claim 6  wherein the adhesive comprises low density polyethylene and the airflow resistive membrane comprises a meltblown polybutylene terephthalate web having an acoustical airflow resistance between about 200 mks Rayls and about 3300 mks Rayls.  
   
   
       9 . A sound-modifying structure comprising a sound-reflecting surface spaced from a semipermeable sound modifying laminate comprising a facing layer and a porous membrane that is substantially impenetrable by molten polyethylene.  
   
   
       10 . A sound-modifying structure according to  claim 9  wherein the facing layer comprises carpet, the membrane comprises a fluorochemical and has an acoustical airflow resistance between about 200 mks Rayls and about 3300 mks Rayls, and the laminate further comprises fibrous material between the sound-reflecting surface and the membrane.  
   
   
       11 . A sound-modifying structure according to  claim 10  wherein the fibrous material comprises recycled shoddy.  
   
   
       12 . A vehicular sound-absorbing structure comprising a decorative layer backcoated with a discontinuous hot melt adhesive layer adhered to a fluorochemically-treated nonwoven airflow resistive membrane having an airflow resistance between 50 and 5000 mks Rayls.  
   
   
       13 . A carpet comprising fibers tufted into a backing backcoated with a discontinuous hot melt adhesive layer adhered to a fluorochemically-treated nonwoven airflow resistive membrane having an airflow resistance between 50 and 5000 mks Rayls.  
   
   
       14 . An acoustical laminate comprising: 
 a fibrous or open cell foam underlayment,    a hot melt adhesive layer,    a fluorochemically-treated nonwoven airflow resistive membrane having an airflow resistance between 50 and 5000 mks Rayls,    a hot melt adhesive layer, and    a decorative layer.    
   
   
       15 . A headliner, trunk liner, hood liner, instrument panel liner or carpet according to  claim 14 .  
   
   
       16 . A nonwoven acoustic insulating laminate, the laminate comprising at least a porous membrane which has been treated so that it has a surface energy less than about 34 dynes/cm 2 , and at least a layer of fibrous material or open cell foam, the laminate being positioned in a vehicle such that the laminate attenuates sound waves passing from a source area to a receiving area in the vehicle.  
   
   
       17 . The acoustic insulating laminate of  claim 16  wherein the porous membrane comprises a meltblown web.  
   
   
       18 . The acoustic insulating laminate of  claim 16  wherein the porous membrane has been treated by topically applying a fluorochemical.  
   
   
       19 . The acoustic insulating laminate of  claim 16  wherein the porous membrane has been treated by topically applying an organosilicone.  
   
   
       20 . The acoustic insulating laminate of  claim 16  wherein the porous membrane has been treated by melt addition of a fluorochemical.  
   
   
       21 . The acoustic insulating laminate of  claim 16  wherein the porous membrane has been treated by plasma fluorination.  
   
   
       22 . The acoustic insulating laminate of  claim 16  wherein the porous membrane has a surface energy less than about 30 dynes/cm 2 .  
   
   
       23 . The acoustic insulating laminate of  claim 16  wherein the porous membrane has a surface energy less than about 28 dynes/cm 2 .  
   
   
       24 . The acoustic insulating laminate of  claim 16  wherein the fibrous material comprises a shoddy layer.  
   
   
       25 . The acoustic insulating laminate of  claim 16  wherein the laminate further comprises a decorative layer comprising at least one of leather, metal, and plastic.  
   
   
       26 . A method for attenuating transmitted sound waves passing from a source area to a receiving area of a vehicle, the method comprising: 
 a) providing a nonwoven acoustic insulating laminate, wherein the laminate comprises at least one nonwoven web which has been treated so that it has a surface energy less than about 34 dynes/cm 2 , and at least a layer of fibrous material or open cell foam, and    b) positioning the laminate so that it attenuates sound waves passing from the source area to the receiving area.    
   
   
       27 . The method of  claim 26  wherein the porous membrane comprises a meltblown web.  
   
   
       28 . The method of  claim 26  wherein the porous membrane has been treated by at least one of: 
 topical application of a fluorochemical,    topical application of an organosilicone,    melt addition of a fluorochemical, and    plasma fluorination.    
   
   
       29 . Tee method of  claim 26  wherein the porous membrane has a surface energy less than about 30 dynes/cm 2 .  
   
   
       30 . The method of  claim 26  wherein the porous membrane has a surface energy less than about 28 dynes/cm 2 .  
   
   
       31 . The method of  claim 26  wherein the fibrous material comprises a shoddy layer.  
   
   
       32 . The method of  claim 26  wherein the laminate further comprises a decorative layer comprising at least one of porous leather, perforated leather, porous metal, perforated metal, porous plastic, and perforated plastic.